The invention relates to an actuating device for an automatic transmission of a motor vehicle.
DE 43 04 250 C1 discloses an actuating device for an automatic transmission. The actuating device has a selector shaft, which can be moved into a position corresponding to the “N” drive setting, irrespective of the position of an electric motor. This makes it possible to tow the vehicle away, even when a transmission control system has failed. Positioning is carried out by an unlocking lever that can be unlocked manually. The unlocking lever is actuated within the interior of the vehicle by an actuating device, which is connected to the unlocking lever by a Bowden line. At the same time, an ignition lock is released by way of a second Bowden line, allowing an ignition key to be withdrawn.
DE 196 43 303 A1 describes a safety device that has an electric parking interlock, which can be unlocked by a spring accumulator in the event of emergency unlocking. The spring accumulator is activated by turning an ignition key in an ignition lock.
U.S. Pat. No. 4,843,901 describes a drive-setting selector device of an automatic transmission of a motor vehicle, in which drive settings can be selected by electric pressure switches. A selector shaft of the automatic transmission is turned to the selected position by an electric motor mounted on the automatic transmission.
If the electric drive-setting selector device fails, a drive shaft of the electric motor can be moved into a desired position by hand with the aid of a tool. For correct positioning, marks indicating the various drive settings are provided close to the selector shaft. In the event of a malfunction, a driver of the vehicle has to leave the interior of a vehicle and turn the selector shaft to the desired position with the tool in an engine compartment. If the motor vehicle is not secured against rolling away by a parking brake or a parking interlock, the driver of the vehicle is at risk of being run over on a slope.
Faced with this situation, it is the object of the invention to propose an actuating device by which the motor vehicle can be operated safely and dealt with conveniently.
According to one aspect of the invention, an actuating device has a drive-setting selector device, which has at least one park position (P) and further positions (R, N, D). The drive-setting selector device can be operated by a driver of the vehicle and, in particular, can be arranged in the vicinity of a steering wheel or in the region of a center console. Selection of the various positions can be effected by displacing or turning an operating lever or by actuating buttons or switches representing the various positions, for example.
The drive-setting selector device communicates via signals with at least one control device, which detects the selected position of the drive-setting selector device. The control device can be identical with a control device that controls functions of the automatic transmission or can be embodied separately.
The control device controls at least one actuator. The actuator can preferably be electric, such as an electric motor, or can be hydraulic or pneumatic. The actuator can be arranged inside a housing of the automatic transmission or outside the housing.
Various drive ranges of the automatic transmission can be selected by the actuator. In particular, the drive ranges correspond to the positions which can be assumed by the drive-setting selector device. In particular, the drive ranges can be selected by turning or axially displacing a selector shaft and/or through the activation of various gear-change elements of the automatic transmission.
The parking interlock advantageously has a parking-interlock wheel, which is connected in a rotationally fixed manner to an output shaft of the automatic transmission. The parking-interlock wheel can be secured in a rotationally fixed manner relative to the housing of the automatic transmission by a pawl. When the parking interlock is engaged, the motor vehicle is thus secured against rolling away.
The parking interlock can be engaged and released by a first device. In particular, the device is actuated by an actuator, which may be identical to or separate from the actuator by which the drive ranges can be selected.
In addition, the actuating device has a second device, by which the parking interlock can be engaged. Engagement of the parking interlock by the second device is performed, in particular, in the event of a malfunction. In the event of a malfunction, the parking interlock can no longer be engaged by the first device. This can be caused by failure of the control device or the actuator, for example.
The actuating device according to the invention allows the motor vehicle to be operated in a particularly safe manner. With the second device, the motor vehicle can be secured against rolling away in any state. In addition, protection against theft is ensured since release of the parking interlock can only be performed by an actuator, for the activation of which a control device is required. The control device operates only when it is activated by an authorized driver of the vehicle.
The automatic transmission can, in particular, be embodied as a planetary automatic transmission, as a continuously variable transmission or as a step-change transmission with an automated clutch and automated gear changes.
As a refinement of the invention, the actuating device has an ignition switch, which has at least two positions (“inactive”, “active”). The ignition switch can be embodied as a rotary switch, a sliding switch or a pressure switch, for example. The ignition switch can be used to activate control devices of the motor vehicle. In addition, the ignition switch can trigger starting of an engine, for which purpose it can have a further position (“Start”). In particular, the ignition switch can be embodied as an ignition lock.
Between the ignition switch and the second device, by which the parking interlock can be engaged, there is an effective connection, which can be mechanical and/or hydraulic and/or pneumatic, for example. The parking interlock can be engaged by the effective connection and the second device.
This refinement is particularly economical and space-saving since motor vehicles generally have ignition switches, that is to say there is no need for an additional component for reliable engagement of the parking interlock.
As a refinement of the invention, the ignition switch has a further position (“emergency actuation”), by setting which the parking interlock can be engaged. This refinement is particularly convenient since the driver of the vehicle can use the ignition switch, which is familiar to him, to engage the parking interlock, particularly in the event of a malfunction, and does not require an additional operating device, the location of which he first of all has to look for.
As a refinement of the invention, the “emergency actuation” position is arranged on the ignition switch in the opposite direction from the “active” position in relation to the “inactive” position. In the case of a malfunction, in particular, the ignition switch must be moved counter to the otherwise customary direction when engaging the parking interlock. This constitutes a particularly reliable refinement since incorrect operation by the driver of the vehicle is made more difficult.
As a refinement of the invention, the ignition switch has a locking device, which allows the ignition switch to be moved only into a position different from the “emergency actuation” position in normal operation of the actuating device. The locking device can be electromagnetic and/or mechanical, for example. When the locking device is deactivated, the ignition switch can be moved to the “emergency actuation” position. The locking device can, in particular, be deactivatable by the driver of the vehicle, deactivatable by a control device or be configured in such a way that it is self-deactivating in the event of a malfunction. The locking device can be embodied in such a way that the ignition switch can be moved only into the “emergency actuation” position in the deactivated state of the ignition switch.
This refinement is particularly reliable since it makes incorrect operation by the driver of the vehicle particularly difficult.
As a refinement of the invention, the ignition switch is embodied as an ignition lock, which can be operated by an ignition key. The ignition lock has a withdrawal prevention device, which allows the ignition key to be withdrawn only when the parking interlock is engaged. The withdrawal prevention device can be electromagnetic and/or mechanical, for example. In the case of an electromagnetic embodiment, the withdrawal prevention device is controlled by a control device. The control device can be the control device that controls the actuator for selecting the various drive ranges; the control device that controls the functions of the automatic transmission; or a separate control device.
This refinement is particularly advantageous since it enables different national legal regulations on the operation of motor vehicles with an automatic transmission to be complied with. It is thus possible to buy just one version of the actuating device in different countries. This is economical since there is no need to develop, manufacture and sell any further versions.
As a refinement of the invention, the ignition switch is embodied as an ignition lock, which can be operated by an ignition key. The ignition lock has a device which allows the ignition lock to be moved only into a position different from the “emergency actuation” position in normal operation of the actuating device. The same device ensures that the ignition key can be withdrawn only when the parking interlock is engaged.
This refinement is particularly economical since just one device can perform two functions.
As a refinement of the invention, actuation of the ignition switch into the “emergency actuation” position is prevented by the effective connection between the ignition switch and the second device for engaging the parking interlock. This refinement is particularly economical since the existing effective connection can perform a further task in addition to engaging the parking interlock in the event of a malfunction.
As a refinement of the invention, the ignition switch has an emergency unlocking device, by which the ignition switch can be moved into the “emergency actuation” position in the event of a malfunction. The emergency unlocking device can be operated by the driver of the vehicle. This refinement is particularly reliable since it makes incorrect operation by the driver of the vehicle particularly difficult.
As a refinement of the invention, the control device communicates via signals with a first sensor, which detects whether there is an ignition key in an ignition lock, and/or with a second sensor, which detects whether a door of the motor vehicle is open or closed. In the event of a malfunction, the parking interlock can be engaged when the ignition key is removed from the ignition lock and/or when a door of the motor vehicle is opened on the basis of a signal from the control device. The signals from the sensors can be evaluated individually or in combination. This refinement can be used especially in vehicles that do not have an ignition key and an ignition lock and in which the engine can be started by a starter button, for example.
This refinement is particularly reliable and convenient since the parking interlock can be engaged in the event of a malfunction without special action by the driver of the vehicle.
As a refinement of the invention, the actuating device has an energy storage device, e.g. a battery. This means that the control device and an actuator, by which engagement of the parking interlock can be triggered, are operational even if the vehicle electrical system fails, for example. This ensures particularly safe operation of the motor vehicle.
As a refinement of the invention, the second device for engaging the parking interlock has a parking-interlock accumulator, by which the parking interlock can be engaged in the event of a malfunction. The parking-interlock accumulator can be embodied as a spring accumulator, hydraulic accumulator or compressed-air accumulator, for example. The parking-interlock accumulator can be embodied in such a way that engagement of the parking interlock can be performed just once; after this engagement, the accumulator must be reset.
This refinement is particularly convenient since the driver of the vehicle does not have to apply a force for engagement of the parking interlock himself but has only to release the parking-interlock accumulator.
As a refinement of the invention, the parking interlock can be engaged independently of the actuator by which the first device is actuated. For this purpose, the parking interlock can be decoupled from the first device. This refinement allows reliable operation of the parking interlock since it can be engaged even in the case where the first device is locked, due to a mechanical defect for example.
As a refinement of the invention, the second device for engaging the parking interlock is in effective connection with a third device, by which an engine bonnet of the motor vehicle can be unlocked. The effective connection can be mechanical, being embodied, in particular, as a Bowden line, and/or hydraulic and/or pneumatic.
This refinement is particularly economical and space-saving since there are generally devices for unlocking the engine bonnet in motor vehicles, and there is therefore no need for an additional device.
All the control devices mentioned can be arranged inside or outside the housing of the automatic transmission.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.